Confirming, and sending the clearest sign of his previously discussed pivot toward Russia and away from NATO and the West, on Tuesday President Recep Tayyip Erdogan announced that Turkey had signed a deal to purchase a Russian surface-to-air missile system, and paid the first installment. The deal cements Turkey’s recent rapprochement with Russia, despite differences over the war in Syria, the downing of a Russian fighter jet over Turkey in late 2015 and the assassination of a Russian ambassador earlier this year, and comes as Turkey’s ties with the United States and European Union have become strained to the point of breaking.

Although the missile purchase from Russia was made public several months ago, Erdogan’s announcement was the first confirmation that Turkey had transferred money to pay for the S-400 missile system.

“Signatures have been made for the purchase of S-400s from Russia,” Erdogan said in comments published in several newspapers on Tuesday. “A deposit has also been paid as far as I know.”

As the NYT writes, “the purchase of the missile system flies in the face of cooperation within the NATO alliance, which Turkey has belonged to since the early 1950s. NATO does not ban purchases of military hardware from manufacturers outside the American-led alliance, but it does discourage members from buying equipment not compatible with that used by other members.”

According to reports in the Russian media, Turkey is to get four batteries of S-400 launchers complete with targeting radar and control posts. Some aspects of the deal are reportedly to be finalized, but Russian officials said the contract furthers Russia’s geostrategic interests.

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Predictably, the Pentagon promptly reiterated its concerns over the deal, which it said undermines inter-operability of weapons systems among NATO allies. “We have relayed our concerns to Turkish officials regarding the potential purchase of the S-400. A NATO inter-operable missile defense system remains the best option to defend Turkey from the full range of threats in its region,” spokesman Johnny Michael said in a statement.

A NATO official in Brussels where the alliance is headquartered, said that no NATO member currently operates the Russian missile system and that the alliance had not been informed about the details of the purchase by Turkey. “What matters for NATO is that the equipment allies acquire is able to operate together,” the official said, speaking on the condition of anonymity as required by alliance procedures. “Interoperability of allied armed forces is essential to NATO for the conduct of our operations.”

However, on Wednesday Turkish President Recep Tayyip Erdogan slammed the critics of Turkey’s deal with Russia, saying Ankara had no intention of waiting for the protection of its NATO allies.

“They have gone crazy because we made a deal for S-400s,” Erdogan said Wednesday in a speech to the ruling AKP mayors in Ankara, as cited by Hurriyet.

“What do you expect? Should we wait for you? We take care of ourselves in every security point. We are taking precautions and we will continue to do so,” the Turkish leader said.

Erdogan criticized the reluctance of US and Israel to authorize supply of combat drones to Turkey as another example of how Turkish security was sidelined by its allies.

“When they did give [drones], their repair and maintenance put us in a difficult position. Now [Turkey] has come to a point where it can produce its own unmanned, armed air vehicles. And now they are uncomfortable with that,” Erdogan added.

Erdogan also dismissed issues of interoperability, brand loyalties or the geopolitical optics of such a sale. “Nobody has the right to discuss the Turkish republic’s independence principles or independent decisions about its defense industry,” the daily newspaper Hurriyet reported him as saying.

“We make the decisions about our own independence ourselves,” he said. “We are obliged to take safety and security measures in order to defend our country.”

As the NYT adds, Erdogan’s announcement — made to Turkish journalists aboard his presidential jet as he returned from Kazakhstan — appeared timed as a response to two judicial cases announced last week in the United States. One is against his presidential bodyguards, who are charged with assaulting protesters when Mr. Erdogan visited Washington this year. The other is against a group of Turks, including a former minister, accused of breaking United States sanctions against Iran. Erdogan has angrily criticized both cases.

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The S-400 SAM is designed to detect, track and then destroy aircraft, drones or missiles. It’s Russia’s most advanced integrated air defense system, and can hit targets as far as 250 miles away. Russia has also agreed to sell them to China and India, both nations who are masters at reverse engineering. Most concerning for NATO, however is that the systems delivered to Turkey would not have a friend-or-foe identification system, which means they could be deployed against any threat without restriction.

Turkey has been weighing options for acquiring long-range SAMs for years. In 2013, Ankara surprised other NATO members by announcing that it was going to purchase the FD-2000 system from China, sparking criticism from Washington. Defense observers speculated that Turkey played the China card to put pressure on its allies and get better terms for buying a NATO-compatible SAM system, such as the US-made Patriot PAC-3. The Chinese deal stalled and was eventually scrapped, with Turkey reportedly unhappy over Beijing’s reluctance to hand over the technology behind the advanced system. Last year Ankara announced that it was in talks with Russia over a potential purchase of the S-400.

Turkey has other reasons for the missile purchase. It needs to cultivate good relations with Russia, and it also needs to build its own military defense, said Asli Aydintasbas, a fellow at the European Council on Foreign Relations. “Turkey wants the deal,” she said, “and Russia is only too happy to drive a wedge into the NATO alliance.”

While NATO’s collective defense should have been sufficient for Turkey – NATO deployed Patriot missiles there during a rise of tensions with Syria in the past – Erdogan lost trust in the West since last year’s failed “coup attempt”, which he slammed repeatedly as a Western plot to oust him, and appears determined to secure his own defense.

Furthermore, the transfer of technology from Russia is attractive to Turkey: Erdogan has spoken also of his frustration at having requests to the United States for drones turned down, and of his satisfaction that Turkey developed its own.

Notably, Erdogan’s announcement of the deal with Russia came after Germany said that it was suspending all major arms exports to Turkey because of the deteriorating human rights situation in the country and the increasingly strained ties. “We have put on hold all big requests that Turkey sent to us, and these are really not a few,” the German foreign minister, Sigmar Gabriel, said during a panel discussion in Berlin on Monday, according to Reuters.

While the purchase of Russian missiles will take cooperation between the two nations to a new level, but is not the first time that Turkey has bought military equipment from Russia. It turned to Moscow in the early 1990s to buy military helicopters and armored personnel carriers. Last year, Russia and Turkey reached an agreement to revive a suspended natural-gas pipeline project.

Meanwhile, as the US military-industrial complex has flourished in recent months following a spike in deals with Saudi Arabia, South Korea and other nations courtesy of rising geopolitical tensions, Russia has remained largely squeezed out of the arms market in Western and Eastern Europe, even in countries that once bought nearly all their weapons from the Soviet Union, has looked for years to NATO’S eastern flank as a promising market and the alliance’s weakest link. It has also sold weapons to Greece, another NATO member and to Cyprus, which is not a member of NATO but houses British military bases and effectively serves as an outpost of the alliance.

Meanwhile, as Turkey’s suspicions toward the West have grown, relations with Russia warmed, driven by the personal relationship between Erdogan and Vladimir Putin. Erdogan has expressed personal admiration for Putin, to the consternation of many European and American leaders, if not President Trump. Erdogan has also shown a preference for the Russian model, with its sense of restoring a lost empire, returning Turkey to a more independent place in the world and rejecting Western democracy.

At the same time, the fact that Turkey belongs to NATO has only increased Mr. Putin’s desire to forge strong relations with Mr. Erdogan despite their differences over the conflict in Syria.

“Mr. Putin and myself are determined on this issue,” Erdogan told journalists about the missile deal.